SE516401C2 - Electrical synchronous machine used in power plants, has processor which measures data for power converter control, from output of co-rotating sensors, and is wirelessly linked with stationary processor - Google Patents

Abstract

A co-rotating processor (10) evaluates the measurement data for power converter (8), from the output of co-rotating sensors (15-17) rotated with rotor (3). Communication units (11,13) are provided to carry out wireless link between the processor (10) and stationary processor (12).

Description

20 25. = -; 0 “51 6 4 Û 1 É °: É": ".: °:" :: "::": 'Éf' "É =:": 2 2 ": * f I? IÄVÄÉ As a means of achieving a control of these quantities, a converter is normally used, which controls the current passing through the rotor windings. By converter is generally meant devices which affect the amplitude, phase and / or frequency of an electric current, which includes AC-to-DC converters, DC-to-AC converters, frequency converters, phase shifters and various types of current amplifier devices and combinations thereof.

The magnetization of synchronous machines with rotor windings, ie. power supply to the rotor windings, can be performed in two ways. It can be done either brushless, using a magnetizer, or with slip rings and brushes. In the latter method, the current to be supplied to the rotor windings is transmitted between the stationary and the rotating part of a synchronous machine by an arrangement of brushes and slip rings. However, such a solution has all the problems associated with movable connectors, such as sparking, disturbances, material wear, etc. Many larger synchronous machines today therefore use so-called brushless magnetization.

Brushless magnetization takes place with the help of a co-rotating feeder and a converter. Axis-rotating converters, in the form of alternating current-direct current converters, have been available for about 25 years as brushless feeders for feeding the field winding in the rotor. The co-rotating co-shaft with the shaft is mainly / usually made of diodes, and the field current is controlled via the stator current of the feeder, so that the electronics of the converter on board the rotor are easy to carry out in traditional analogue technology.

An example of a brushless feeder design can be found in the ABB brochure "Brushless exciter", SEGEN / HM 8-001. The brochure states that the feeder is an AC machine whose stator is provided with pronounced poles and whose rotor has a three-phase AC winding for feeding a converter. The DC voltage of the inverter is then connected to the field winding of the synchronous machine. The voltage of the synchronous machine can be regulated by influencing the magnetization of the feeder via its field winding. lO 15 20 25 :: ".. 30 '516 4 0 1 ï' = - ï" = '= f = IIa = IIs. a "s: ïï:." ïí 3 A disadvantage of a brushless feeder of the above type, with a converter based on diodes, is the slow dynamics of the system. With the use of a so-called PSS ("Power System Stabilizer"), it is necessary that the excitation system has a sufficiently short response time.

This can be achieved by making the AC-DC converter with thyristors. Such a system is described in U.S. Pat. No. 3,671,850, which uses radio communication to determine the control angle of the thyristors in the rotary thyristor rectifier. Analog technology is used here, which makes the system difficult to adapt dynamically, when changing parameters included in the control, such as the resistance of the rotor.

When using slip rings and brushes, both the AC-DC converter and the control electronics are typically stationary, with the pre-regulated current being transferred to the rotor.

A special embodiment of magnetization of an electric machine rotating at a constant speed is described in a patent application PCT / EP 98/007744, for "Power control ow control" in a transmission line. The stator windings of the electrical machine are here connected in series with the conductor of the transmission line without a connected neutral point. The rotor of the electric machine is equipped with two or three 90 and 120 degree, respectively, electrically displaced direct current rotor windings for regulating the amplitude and phase of the voltage of the electric machine. The rotor windings are fed via a co-rotating excitation feeder and converter (AC-DC converter) for each of the rotor windings. The same patent application further describes a more developed “Power control ow control” with a second electric machine connected to the same shaft as the first electric machine, which, however, is connected in a shunt to the transmission line but also has a co-rotating converter. However, control and regulation are discussed sparingly.

Since installations of large synchronous machines constitute large investments, it is of particular importance to ensure that synchronous machines are not operated in such a way that there is a risk of damage to the machine and unplanned downtime. 10 15 20 25 ... . ... - -30 I b ... 516 4Û1 zærza: fur; . "= - :: -": == "= = - .: 4 2": '-. = :: = :: =' = .. == .. = '- .. == .. = = Therefore, there are safety devices connected to a number of synchronous machines, which must monitor the condition of the synchronous machines and in an appropriate manner interrupt or limit such operation that may damage the machine or be unfavorable for the operation of the power grid. The safety devices can consist of clean protection, which shuts off operation in the event of detected faults. They may also consist of limiting devices which suitably alter or restrict operation to permissible conditions.

In the following description, it is assumed that the working windings of the machine are in the stator and that field current (excitation current) is thus in the rotor. However, this is not important for the basic idea of the invention.

The limits for how hard a synchronous machine can be used are often set by considerations regarding temperatures, e.g. the temperatures of the stator and field windings. The currents in the windings permitted by the protection and limiting devices are generally estimated with the aid of simple theoretical models. For the field winding, a limit is typically set for the current of the excitation equipment. This can have a limit at e.g. nominal field current. Larger machines are often equipped with a field current limiter which, in addition to an instantaneous limiter, can contain a time delay that allows a certain overcurrent for a shorter period. However, this limitation is static and does not take into account the actual thermal condition of the synchronous machine.

The stator winding on AC machines is normally protected by an overcurrent protection. In the event of an overload of the machine, such as the current exceeding a limit given by the rated power, the machine is switched off.

Synchronous machines may be equipped with a stator current limiter and / or sub-magnetization limiter. These limiters can either automatically regulate the field current or give an alarm to the machine operator who can manually regulate the field current and thus control the reactive power '10 15 20 25 I nu sn »nn» 30 1 na »-516- 401 safu: z-: æ ": =." =:.: 5 5 ": '-.-' :: = :: = '= .. == .. =' - .. == .. = = so that the operating point is maintained within the allowable the working area of a well-known "P-Q pie chart" which is often referred to by those skilled in the art as a capability chart.

AC machines with an output of more than 5 MVA are today equipped with resistive temperature meters (eg Pt100 elements) which are placed in or near the stator winding. These provide good information about the working temperature of the winding. These are connected to a protection that disconnects the machine when the temperature reaches a certain limit value. These limit values are typically determined from the temperature class or from measurements during commissioning of the machine.

A problem with machine protection and machine limiters according to the state of the art is that in many cases they are based on rough static models of loss generation and management as well as temperature rise. The actual conditions such as variation in ambient temperature are generally considered very little. In order for protection to be obtained even for rather extreme conditions, large safety margins must be used. In less extreme cases, this leads to the protections triggering unnecessarily early in a process.

Furthermore, if a load drop or fault in the power grid causes an unfavorable distribution of reactive and active power, this can easily lead to an increase in temperature and / or current in certain parts of an AC machine. If the protection is set at a far too low level, such a power grid situation can lead to the machine's protection being activated and the machine being switched off. This in turn can lead to a worsening of the state of electricity. Other types of potential faults and accident risks are also interesting to monitor. Isolatlion states such as earth fault leakage current detection and mechanical machine conditions, such as mechanical stresses, vibrations, cooling temperatures and fates, are possible sources for detecting operational changes that could lead to various types of breakdowns. Surveillance of stationary parts can be easily provided and is well known in the art. Monitoring of rotating components is more difficult and has so far been limited to a few special cases. 10 15 20 25 r »n 1 u m» i I u: rn 516 401 nam; : nya 53-22- ": =;" = '- = 6 2 ":' -.- ':: = :: =' = .. == .. = ° - .. == .. = = ST Chow and CH Chew have in "Radio telemetry system for vibration measurement of rotating machinery", Conf. Proc. TENCON'84, Int. Conf. On Consumer 86 Industrial Electronics 85 Applications, New York, NY, USA, 1984, pages 3 5, described a device with wire strain gauges on the rotor blades of a turbine, where the signals are transmitted to a measuring and analysis instrument for evaluation. "Unique sensor applications for hydroelectric generator rotor-mounted sensor scanning technology", by J .S.

Edmonds and T.L. Churchill, IEEE Techn. Appl. Conf, Northcon / 96, Conference record, IEEE, New York, NY, USA, 1996, pages 73-77, are also examples of transmission of measured values from rotating parts. The same is true of "The measurement of strain on a laminated disc fl yWheel" by A. Owens and P. Williams, Int. Power Generation, Vol. 6, no. 6, 1983, pages 24-27 and "Rotor monitoring and protection for large generators" by R.H. Regan and K.

Wakeley, Proc. Electrical Machines and Drives, 1995, pages 203-207.

Common to such systems is that a special solution for the transfer of measurement data takes place from a rotating sensor to a central measurement and evaluation system. Continuous monitoring can thus take place, but with the help of a considerable amount of transmitted data. In cases where the results are used to control the device, such control takes place according to conventional principles.

Due to the fact that synchronous machines involve large and expensive installations, the devices are often dimensioned to withstand normal operating conditions with large margins, especially concerning the electrical insulation. In addition, margins normally occur in several stages, which has the consequence that the total margin becomes unjustifiably large. This can happen e.g. in that a manufacturer of an insulating material indicates a certain nominal temperature, at which the material has a certain service life. Such a temperature is usually given by a certain margin. The material can then be classified in a material class, whereby the temperature limit of the class is normally used for all materials included in the ~ class. Furthermore, a machine builder uses the material 10 15 20 25 "', 30 ° .516 401 7 in his construction, adding his own construction margins.

Finally, the supplier of a machine can specify certain permissible operating conditions, but when an operator prepares its own operator instructions, additional safety margins are added to compensate for minor failures in operation. In many cases, this gives a total margin that is so large that only a too small part of the material's possible performance is utilized, which today in many cases is not economically optimal.

The problems with synchronous machines according to the state of the art are that they to a large extent lack a reliable and dynamic control in the current situation regarding e.g. magnetization of the rotor. Furthermore, there are design margins built into today's synchronous machines that are not used efficiently. In addition, the prior art protective devices for synchronous machines are unsatisfactory in terms of flibility and monitoring capabilities.

SUMMARY A general object of the present invention is to provide a synchronous machine with intelligence in order to be able to achieve in an improved manner an optimal control of the operating conditions of the machine. An object of the present invention is also to use measurements of electrical and mechanical quantities associated with the rotating parts of an electric machine as a basis for the control. In the present description it is meant that the term mechanical quantities also includes thermal quantities. Another purpose is to use continuous monitoring of critical quantities in the synchronous machine to utilize considerable design margins for efficient operation and a visible protection of the machine. A subordinate object of the present invention is to provide an electric machine, where processing and / or measurement of quantities associated with the rotating parts of the electric machine takes place locally in direct connection with the relevant part of the electric machine. A further object of the present invention is to provide an electric power plant with increased possibilities for planned and / or coordinated power changes. 10 15 20 25 u vv »- o o ø ø o o oo n. In general terms, a converter device is provided, a winding rotor provided with a co-rotating synchronous machine, which comprises a processing unit, and a similarly co-rotating communication unit for wireless information transmission to a stationary unit. The rotor also has at least one co-rotating sensor for measuring mechanical and / or electrical quantities associated with the rotor.

BRIEF DESCRIPTION OF THE DRAWINGS The invention and further objects and advantages achieved thereby are best understood by reference to the following description and the accompanying drawings, in which: Fig. 1 of the invention, with brushless magnetization; shows a block diagram of an embodiment according to the present Fig. 2 shows a block diagram of another embodiment according to the present invention, with magnetization via slip rings and brushes; Fig. 3 shows a block diagram of a third embodiment according to the present invention, with double rotor windings; Fig. 4 is a combined capability and pointer diagram for a synchronous machine in generator operation; Fig. 5a shows a block diagram of an electric power plant with two synchronous machines according to the present invention; Fig. 5b shows a block diagram of communicating electric power plants; Fig. 6 shows a circuit diagram of a control method for a synchronous machine according to the present invention; and control method for an electric power plant according to the present invention.

Fig. 7 shows a flow chart for a DETAILED DESCRIPTION 10 15 20 25 :: ..: 30 5 1 6 I 0 1 von ~ ovnnnn .... nno '' ° "'' '2' Z z I! '.. 'f! I PJ: infiof 2.' A basic embodiment of the present invention is schematically illustrated in Fig. 1. A synchronous machine, generally designated 1, comprises a stator 2 and a rotor 3. The stator 2 is provided with alternating current windings 4, through which, during operation, an alternating current is provided, which is provided by supply connections 5. The rotor 3 is arranged around a rotating shaft 6, and comprises rotor windings 7 or field windings. excitation current controlled by a converter 8.

According to the present invention, the synchronous machine 1 is provided with a processing unit 10 co-rotating with the rotating shaft 6. The co-rotating processing unit 10 is connected to a communication means 11 co-rotating with the rotating shaft 6. This communication means 11 is arranged to transmit and receive data through a wireless information transfer. The co-rotating processing unit 10 is also connected to the converter 8, for controlling its operation. A stationary processing unit 12 is connected to a stationary communication means 13. The stationary communication means 13 is arranged to transmit and receive data through the wireless information transmission with the co-rotating communication means 11. The stationary processing unit 12 is preferably also connected to further external processing units via at least one communication device. 14.

A number of co-rotating sensors 15, 16 and 17 with the rotating shaft 6 sense mechanical and / or electrical quantities associated with the rotor 3, and the sensors 15, 16 and 17 are connected to the co-rotating processing unit 10 for transmitting measurement data. In the present embodiment, the sensors 15 and 16 measure the temperature of the rotor winding 7 and the sensor 17 measures the actual magnetizing current of the rotor. Similarly, a number of stationary sensors 18, 19 and 20, which sense mechanical and / or electrical quantities associated with stationary parts of the synchronous machine 1, are connected to the stationary processing unit 12 10 15 20 25 '516 4 01:': ": : "::": - If * "É °:":. ~ '- 10 for transmitting measurement data. In the present embodiment, the sensors 18 and 19 measure the temperature of the stator winding 4 and the sensor 20 measures the actual current of the stator. the measurement data transmitted from the co-rotating sensors 15, 16, and 17, and any data received from the stationary processing unit 12. Based on this processed data, the co-rotating processor unit 10 controls the operation of the converter 8 in a suitable manner.

This basic concept makes it possible to control the synchronous machine 1 in a dynamic and efficient manner. The quantities associated with the rotor 3 are measured locally, which normally gives a greater reliability than remote measurements. This reliable measurement data is sent to the co-rotating processing unit 10 via fixed connections, which have very large bandwidths and thus do not constitute an obstacle to communication. The co-rotating processing unit 10 locally processes the received measurement data, and can on this basis give control signals to the converter what a continued operation should look like. The aspects of the magnetization of the rotor which are determined by quantities obtained from the rotor are preferably controlled by signals which are processed entirely within the rotating part of the synchronous machine. The extension thus provides a double function. On the one hand, it provides an actuator or actuating means for controlling the desired operation of the machine unit (such as the one described below), determined, among other things, on the basis of external considerations or wishes. On the one hand, it provides a monitoring device for the machine through the possibility of measuring local quantities.

If measurement data from the co-rotating sensors 15, 16 and 17 causes some action concerning non-rotating parts of the synchronous machine 1, the co-rotating processing unit 10 extracts this data and transmits it to the stationary processing unit 12 via the communication means 11, 13. The stationary processing unit 12 takes then take care of this data for further processing. 10 15 20 25 D I I ... 30.

I I Oil. _516. Similarly, if data originating from the stationary sensors 18, 19 and 20 is important for the control of the converter 8, the stationary processing unit 12 extracts appropriate information, and sends it via the communication means 11, 13 to the co-rotating processing unit 10. This also applies to data and instructions obtained from elsewhere and intended for the co-rotating processing unit 10. The co-rotating processing unit 10 then controls the converter 8 by means of obtained data.

The control of the synchronous machine can, as indicated above, also include "external" data, which can consist of technical, financial, administrative and other control information. The actual data exchange with information about the state of both the synchronous machine and the electric power grid can take place in close connection with the synchronous machine, for example via various monitoring units, which are described further below.

By placing a processing unit co-rotating with the rotor, one obtains an opportunity for local processing of locally obtained data. This minimizes the amount of data that must be transferred between stationary and moving parts. The location of the co-rotating processor unit also provides an opportunity for autonomous operation of the rotor, in the event of interruptions in communication with stationary parts. A fault in the communication devices does not have to mean an immediate shutdown of the entire machine, but the machine can continue to run, albeit more carefully. The co-rotating processing unit can then control the operation of the rotor according to predetermined guidelines independently of the stationary parts.

Those skilled in the art realize that redundancy can also be used in communication, ie. provide alternative communication routes, if the regular communication is switched off. Such communication can e.g. consist of brushes and slip rings or parallel similar communication paths, which are activated when needed. lO 15 20 25 4Û1 .._: .._._ gg_. : nu-E = --._. ;;. In the embodiment shown in Fig. 1, a so-called inverted synchronous machine 26 is used as a magnetizing machine. DC converter 21 with suitable alternating current The alternating current-direct current converter 21 is controlled by the stationary processing unit 12, so that the stator 24 of the magnetizing machine 26 is supplied with a suitable direct current. 8. The converter 8 in this case is preferably a thyristor rectifier.

In an alternative embodiment, an asynchronous machine with fl phase windings can be used as a magnetizing machine. This has the advantage that it can supply energy even to a stationary rotor. 2 shows another embodiment of the present invention.

This is largely similar to the one in fi g. 1 and equal parts are denoted by the same reference numerals and are not discussed further. Only the differences that are described below. In this embodiment, an arrangement of slip rings and brushes 31 is used to transmit the excitation current to the rotor 3. Information regarding the desired control of the imaginative current is in this case transmitted from the co-rotating processing unit 10 to the stationary processing unit 12. A converter 30 is then controlled by the stationary processing unit 12 according to the directives obtained from the co-rotating processing unit 10. The converter 30 is in this case placed stationary, which means that the need for communication between the processing units 10, 12 generally increases.

Fig. 3 shows a further embodiment of the present invention. This embodiment also has great similarities with fi g. 1, and equal parts »are denoted by the same reference numerals and are not discussed further. Only 10 15 20 25: ”30 516 401 13 the differences that are described below. The rotor 3 is provided with two field windings 38, 39. These field windings are arranged with offset magnetic shafts. The windings 38 and 39 are supplied with current from a double converter 40 via the connection lines 41 and 42, respectively. As in fi g. l is the embodiment in fi g. 3 provided with a synchronous machine 26 as a magnetizing machine. The device with double field windings has certain advantages in terms of controllability, stability etc. Such a type of machine is advantageously used together with an electric machine according to the previously mentioned patent application PCT / EP 98/007744.

The rotor 3 in the embodiment in Fig. 3 is provided with a number of additional sensors 43-46, which are connected to the co-rotating processing unit 10. Two sensors 43, 44 are arranged to the connecting lines 41 and 42, respectively, in such a way that they can sense of both the current and the voltage in the respective connection line 41 resp. 42. The sensors 43 and 44 are also arranged to detect disturbances on the current and voltage signals, respectively, whereby they can also be used as detectors for partial discharges, PD. This is described in more detail below.

A vibration sensor 45 is arranged at the rotor body for detecting the vibrations of the rotor, and a torque sensor 46 is also arranged at the rotor shaft 6, to measure the shaft torque. These functions are also described in more detail below.

It is obvious to the person skilled in the art that such additional sensors 43-46 are not particularly useful for the current. 3, without additional sensors can be present together with any type of synchronous machine.

The angle between the voltage vector and the so-called The q-axis, determined by the rotating magnet fl fate, is called the load angle. This angle is a mechanical quantity which can be measured via a sensor co-rotating on the rotor by, for example, determining when the voltage vector assumes its maximum in relation to the rotating magnetic fl fate vector. The loading angle is 10 15 20 25 b I. 5 l - 516 - 401 14 an important parameter for determining the stability properties of the generator with respect to the external electric power grid, which is further described below.

An electrical quantity that can be measured from the stationary stator side is the phase angle, which consists of the angle between voltage and current on the stator side.

Recent developments in e.g. insulation materials for large machines, in terms of thermal aging, manufacturing methods, etc. have made it possible to increase the utilization of the machines' capacity. This is discussed in more detail below. However, these advantages and opportunities cannot be so easily exploited under operational conditions, unless reliable operational information is available. Protection and control of stationary components, such as stator windings and bearings are quite common today. This makes it possible to utilize the capacity of the machines in terms of the stationary parts. Monitoring of the rotor operating conditions is not as common today, however, but is nevertheless very important for an economical utilization of the machines. For good utilization and relevant protection of electrical synchronous machines, it is, among other things, of interest to measure the actual rotor winding temperature. This quantity contains a lot of information about the operating conditions of the rotor. In addition, it may be of interest to also, preferably simultaneously, measure the actual rotor currents, rotor voltages, rotor vibrations, partial discharges in rotor insulation, rotor insulation resistance, shaft torque and load angle. If damping windings are used, corresponding quantities are also of interest to know.

Furthermore, the condition of the insulation is important for the control and planning of the operation of the machine. The condition of the insulation can be monitored by measuring either continuously or intermittently of different quantities. The methods will vary depending on the type of winding and voltage. By measuring the insulation resistance between winding and earth (iron parts in the machine), errors in the insulation can be detected, such as. mechanical wear, 10 15 20 25 v: u a »in - 30 n p in: 516 1401 azzwa:" 15 2 "; :: = - - soiling and absorption of moisture. For the rotor winding this can be done by measuring current and voltage (possibly by using a measuring bridge for increased accuracy) and for a stator winding you can do the same by measuring the leakage current. Partial discharges (PD) occur in cavities in the insulation but can also be discharges in air between the insulation and iron parts of the machine. In the stator, the winding insulation is normally made with a semiconducting outer coating and measurement of PD therefore gives a good indication of the winding insulation itself.

The discharge level is normally quite high in traditional insulation (typically greater than 10,000 pC) and it is usually of interest to measure changes in the discharge level to detect the deterioration of the insulation. For traditional design of the field winding in the rotor, the voltage is quite low and therefore a semiconducting coating between the insulation and the iron parts is not needed. Measurement of PD will therefore not have the same value for a traditional design. However, changing the design of the rotor winding such as the use of two separate windings as mentioned above and / or increased voltage level transient for increased dynamics in the control may make it relevant to measure the values of partial discharges to monitor the state of the insulation. Measurement of the insulation resistance and / or PD can also be used for the regulation of the actual operation of the machine. You will e.g. during a strong temporary overload of the machine to get mechanical stresses between the winding and the iron in the machine because the temperature difference is large. "In the worst case, this can damage the insulation and continuous measurement of PD can then be used to limit the application in the event of temporary overload of the machine. Overload of the machine is further discussed below.

Additional quantities that may be of interest to measure can e.g. be the mechanical vibrations in the rotor. A change in the appearance of the vibration spectrum can indicate incipient mechanical problems, and can also lead to a change in operating control, in order to avoid inconvenient breakdowns. 10 15 20 25. . . '30. 516 401 16 The shaft torque is also information that is of interest for controlling the synchronous machine. Such quantities can be measured in a number of conventional ways, e.g. through wire strain gauges mounted on the shaft. With the help of these sensors, rotating moments, both static and oscillating, can be easily detected.

Shaft torque information can be used, for example, to protect large turbomachines against subsynchronous resonance, SSR. During the interaction between the electricity grid and a turbo generator, SSR can lead to torsional cooperation which results in heating of the shaft, which in turn can lead to a breakdown. This type of destructive torsional interaction can occur if there are "unfortunate" relationships between the natural frequencies of the long shaft in a large turbocharger (including generator and turbines) and the power grid. The risk of subsynchronous (0 - 50 or 60 Hz) resonances occurring is greatest for large turbogenerators in the vicinity of series-compensated power lines.

In the following, it will be described how and why one wishes to control a synchronous machine. Figure 4 shows a capability diagram corresponding to a synchronous machine in stationary operation. The synchronous machine is assumed to simplify the reasoning of having a round rotor. P denotes the active power and Q denotes the reactive power to / from the machine. In Figure 4, it has been assumed that the pole voltage has its rated value Us, IA denotes the stator current and jXs denotes the synchronous reactance. An internal magnetomotor force EA, which is controlled by the field current IF, is formed. The current in the windings has specified rated values IFN, IsN, which should not be exceeded under stationary conditions. Thus, permissible stationary operating conditions are limited to an area within the stator current limit 57 and the field current limit 56, where both IFSIFN and IASIAN. This means that area 53 is not stationary allowed because IA is restrictive and area 54 is not stationary allowed because IF is restrictive. The rated effects PN and QN correspond to the state when both stator and rotor currents assume their rated values. lO 15 20 25 x I> rn i n>: - O n »nn a» p a 516 401 17 When using a synchronous machine in sub-magnetized operation, further restrictions occur. One limitation is the load angle which for a synchronous machine generally increases with decreasing magnetization at constantly converted active power. This means that if the operating point is moved far enough to the left in ñgur 4, the load angle will eventually reach the stationary (theoretical) maximum value 90 degrees, when the machine becomes unstable.

This is a further limitation of the useful area in the PQ diagram. Thus, there is a stability limitation 58 for undermagnetized operation, which may follow the distance outlined in Figure 4. This means that the area 59 is not available for operation.

Additional limitations can be found for different types of synchronous machines, which contribute with further restrictions in the capability diagram, e.g. p.g.a. heating of reversals, field current limiter for minimum current etc. In the following discussions, however, we will neglect such effects, in order to keep the description simple and easy to understand.

However, the principle of the invention also applies to other limiting factors.

Any control of the operating conditions of the machine is thus limited to an area 55. A stationary operating condition is given by the effects P1 and Qi, which are within the area 55.

In today's electric power grids, the available reactive power Q is often of great importance.

Since there are facilities that can be both sources and depressions for reactive power Q, it must be possible to obtain a balance. It is therefore sometimes of interest that e.g. change the reactive power Q, which the generator "delivers" or "consumes" (source or lower). According to IEC 34-1, sect. 9, a synchronous generator with apparent rated power SN and its rated power factor cos cpu is marked. From these data, active and reactive rated power can be calculated (PN or QN).

Corresponding reasoning can be applied to synchronous motors. If the machine operates at rated power, PN and QN, it is quickly realized that an increase in the reactive power Q cannot take place without exceeding the rated currents e IFN and IAN. It is relatively common for the generator to operate in the vicinity of PN, 10 15 20 25 l I. - 30 516- 401 v fi ræa: = "== '_ É; .z" :: ïï: _ "ïïš" š 18 2 "; ° -. =: Ii - while the reactive power can be varied according to the need in the electricity grid. The possibilities to deliver or consume reactive power depend on where in the capability diagram the generator worked before the change.

These possibilities are determined according to the state of the art by static design margins and calculation models.

The temperature of the rotor windings in a synchronous machine is a limiting parameter for the synchronous machine's ability to produce electrical torque as well as its ability to produce reactive power via the stator winding to the mains. Limits for temperatures and currents are often set to protect the machine from destructive overload. However, non-hazardous synchronous machines often have a large thermal margin by the designer and operator incorporating safety margins in the design of the machine or by gaining new experience values since the machine was put into operation. Normalization, customer requirements, uncertainty in dimensioning and inherent tolerance in insulation margins, today give large electricity generators and motors a significant thermal capacity that can be temporarily used to increase the power on the machine.

However, by being able to reliably measure important quantities, it is possible to obtain a safe way of monitoring the synchronous machine so that no damage occurs. This means that you consciously during e.g. shorter periods may exceed nominal values of currents, voltages and temperatures, without compromising the operational operation of the synchronous machine. By introducing a monitoring, the limits of the operating conditions can thus be treated in a much more fl visible way. The fixed limitations according to the prior art can thereby be treated in a more exemplary manner according to the present invention. This means that some of the restrictions shown in Figure 4 no longer have to be absolute restrictions, but deliberate and supervised exceeding of these limits may in some cases be allowed. One possibility to expand the area for possible operating points is to consciously allow an accelerated obsolescence of the insulation material, ie. a 'shortening of service life, by allowing the machine to operate at a higher temperature than 15 15 20 25 o rn io »nrao vv: op 516- 401 aæffv -. which is stated nominally. Such an operation can e.g. towards an increased economic return on this operation. One can thus "sell off a piece of the life of the machine" if desired.

In a synchronous machine you can easily control the currents through the rotor windings, both in terms of phase and amplitude. Such control of _ e.g. a converter means can thus be used to change the operating point in the capability diagram in fi g. 4. Under controlled conditions, the operating point can then e.g. for fl be moved outside the area 55, which provides opportunities for an flexhaustible utilization. Similarly, the operating point can also be changed when measurements indicate that there is a probable fault in the system, which should lead to a careful use. The operating point can then be fl switched to a very conservative operating condition with extra safety margins, until the causes of the fault indications are investigated. If e.g. the rotor vibrations increase in an unjustified manner can e.g. the shaft torque arising from the choice of rotor current is changed so that the mechanical load on the rotor is reduced.

According to the present invention, the synchronous machine is provided with a number of sensors, preferably at both stationary and rotating parts. These sensors can be of the types discussed above, or for measuring other quantities that may conceivably influence the desired operation of the synchronous machine.

The sensors are connected to the processing units 10, 12, where a local evaluation of the measured values is performed. The data transmission can here take place through fixed connections, which can easily provide the desired bandwidth. In e.g. In cases where measurements from a stationary sensor indicate that the rotor current is to be changed, a transfer of information must take place between the stationary parts of the synchronous machine until then. rotating parts. In the same way, a transfer of information in the opposite direction may also be necessary. However, the amount of data transferred is reduced by the local processing in the stationary 12 and the co-rotating processing unit 10, respectively. An example of how to reduce the data amounts is e.g. that instead of transferring stationary values only transfer measured values at observed changes.

Since the operating conditions are predominantly stationary for a large 10 15 20 25 I I m.

'O i n »ll ñ - 51-6 401 ilzäï: .z" §; ïï; -Ä'¿Éš "š 20 synchronous machine, the amounts of transmitted data are significantly reduced. The more processing power and intelligence available locally, the less the requirement for information transfer between the processing units.

By placing the processor capacity locally, close to the measuring points, the control of the converter can also be made very fast and flexible. The dynamics in the control of the converter in e.g. fi g. 1 no longer has to rely entirely on control from the stationary parts, but can take place directly from the local co-rotating processing unit 10, in terms of the information likewise obtained from the co-rotating parts.

According to the invention, the transmission takes place wirelessly between the rotating and stationary parts. A solution with transmission via slip rings and brushes would in principle be possible, but since data transmission in this way is often associated with high levels of interference, mechanical wear and uncertainty in reliability, this is not recommended. Wireless communication of different types can be used. Transmission with inductive coupling can be used. Frequency modulation and time division multiplexing are preferably used in such cases. However, inductive coupling normally requires the addition of an additional mechanical unit to the rotor shaft, with corresponding stationary parts. This undesirably increases the construction length of such synchronous machines. Transmission through different types of light signals, such as IR or visible light is also possible. Infrared communication according to IrDA (Infrared Data Association) is developing rapidly and standardized systems are now available. Solutions are available e.g. by Counterpoint Systems Foundry, Inc.

In a preferred embodiment of the present invention, radio communication is utilized for the wireless Radio technology is well developed for such applications as a result of the information transmission. '10 15 20 25 ..

I I .. - 30. ... 516 491 21 mobility requirements for computers and telephone equipment. Converters of a conventional type normally give rise to electromagnetic interference of various kinds. However, these disturbances are normally mainly below a frequency of 100 MHz, so carrier frequencies above this value should be selected for the communication. Converter disturbances thus do not significantly affect communication. There are license-free frequency bands, such as the so-called

The ISM band (Industrial-Scienti fi c-Medical), which is used for short-distance communication and which works in electromagnetically disturbed environments.

The frequency band at 2.45 GHz is e.g. of great interest.

The article "Bluetooth - the universal radio interface for ad hoc, Wireless connectivity" in Ericsson-Review, vol. 75, no. 3, 1998, p. 110-17, by J.

Haartsen, describes commercially recently available technology for digital communication. Bluetooth is a radio interface in the 2.45 GHz frequency band, which allows terminals to connect and communicate wirelessly via a wireless LAN (local area network) with short range. In Bluetooth, each device can simultaneously communicate with your other devices. Bluetooth uses spectrum hopping technology to divide the frequency band into your hopping channels. During a connection, the transmitters jump from one channel to another in a pseudo-random manner. Wireless communication of up to 721 kbit / s can thus be ensured in the present invention between rotating and stationary parts of the synchronous machine.

A preferred embodiment of the present invention utilizes digital communication. In recent decades, there has been a clear trend to miniaturize electronics for signal processing. Telecommunications can be said to be almost completely digital today in its essential parts. Digital communication today has very well-developed methods for data compression, filtering, error correction, etc., which is not available in the same way in analog communication. Signal processing in control and regulation circuits has also been miniaturized and it is easy to implement internal digital signal processing in e.g. inverters, both "AC-DC-converters" and "AC-DC-converters". "i 22 2%:; =: z technology does not add value, as the digital resolution in terms of both amplitude and time is large enough. Digital communication is also preferred due to other aspects such as the ability to set and tune the parameters of the control circuits remotely An initial parameter setting can thus be changed during operation to a modified parameter setting based on previous operating data.

The stationary processing unit can be placed in such a position that it can operate under normal conditions and preferably consists of a conventional microprocessor, which are well known to those skilled in the art. This is therefore no longer described. The co-rotating processing unit, on the other hand, is exposed to more abnormal conditions, e.g. centrifugal forces, vibrations and elevated temperatures. These environmental conditions must therefore be taken into account when choosing a processor and mechanical design of this as well as attachment thereof.

Such processors are available today, mainly for military use, where the purpose e.g. is to provide reliable shock protection.

Transmission of both reactive and active power contributes to power losses in electric power plants and electric power grids. In this application, electric power plant means a plant comprising a group of synchronous machines, which are located within a limited area and are operated in a coordinated manner and which preferably belong to the same operator. An electric power plant according to the above definition can typically consist of a number of synchronous machines, transformers, cables, cables, busbars, disconnectors and switches as well as associated measuring and adjusting devices. The power conversion of the electric power plant can be affected by the machine as well as other parts of the plant such as phase compensation equipment, to which shunt reactors as well as shunt and series capacitors can be counted. Other components in the power conversion process consist of, for example, HVDC (High Voltage Direct Current) and FACTS (Flexible AC Transmission Systems) components as well as power electronic power converters for industrial and distribution applications. The above-mentioned components can also - be used to control the stationary and transient behavior of the electric power grid in 10 15 20 25 516- 401 23 2 ": '=. = Both normal operation and in the event of a fault. typically years spread over a wider geographical area.

Furthermore, a lack of reactive power, or an unfavorable distribution of it in an electric power plant or an electric power grid can lead to so-called voltage collapse. This is especially important in connection with major faults in the power grid, e.g. when larger generators or motors suddenly fail. When this happens, the properties of the power grid change. Various regulators in the electricity grid or power plant will try to maintain the frequency and voltage within the predetermined limit values. This can be done today, among other things, by changing the active and reactive production of generators and by changing the conversion ratio through winding coupler control in transformers. However, on some occasions it has been shown that this has not been enough. If the need for reactive power is greater than what the electric power grid can satisfy, then the transmission capacity in the electric power grid can collapse very quickly by the maximum point on the so-called The PV curve is passed or by further disconnections of the remaining production units due to overload. The limitation in the amount of transmitted power is due in many electric power grids to a lack of reactive power, especially in critical places and not to the fact that thermal limit values for transmission lines are exceeded.

It is therefore of great importance for an operator of an electricity network or power plant to be able to control the voltage of the electricity network or power plant, to maintain an appropriate distribution of sources and depressions for reactive power, and to be able to change this distribution for shorter periods. Reactive power, in contrast to active power, can not be transported any longer distances. This means that reactive power is a "local" resource which must be made available in the area where it is needed, for example after a disturbance. The reactive power is closely related to the voltage in the electricity grid, while the active power is similarly strongly linked to the frequency. lO 15 20 - 51-6 401 s '= a "=' -..- ° -. ° '==" = 62-21- "ïísï 24: f :: = :: =' = .. ==. . = “-..----- = One way to control the reactive effect is to introduce phase-compensating elements in the electric power grid or power plant.For large and complicated grids, especially if the load changes nature from one time period to another, such solutions require comprehensive analyzes and simulations to optimally determine the location and electrical power of these phase compensators. In addition, procedures are required for controlling them for different operating conditions in the network. AC machines, such as synchronous machines, to cause them to change the reactive power in view of the current situation in the power grid or power plant. react va resources (at least locally) together with various types of disturbances in the electricity grid. For example, if a disturbance leads to a reduction in available reactive resources, this may result in a voltage collapse. It is important that the excitation or winding temperatures of the synchronous machine, when stationary, do not exceed their nominal values. Optimal utilization of available resources can thus be an important factor in ensuring the operation of electricity grids. Phase compensating equipment, together with the possibilities for an improved utilization of the reactive resources in synchronous machines, thus constitute important resources for controlling power flows in the electricity power networks.

However, the present invention provides opportunities to more efficiently and efficiently utilize various existing margins in the machine to e.g. be able to increase the reactive power without reducing the overall utilization of the machine. Synchronous machines according to the present invention can thus be used by an electric power grid or electric power plant to balance the ratio between active and reactive power, especially in critical situations. 10 15 20 25 C30 516. 401 25 The concept of utilizing construction margins can thus also be carried out at the level of electric power plants or power grid levels. Figs. 5a and 5b schematically show an electric power plant in which a number of synchronous machines 62 control equipment for the synchronous machine a machine unit 71. Each machine unit 71 forms part of. Together with the machine constitutes an electric power plant (according to the previous definition), which via power lines or cables 61 is connected to an electric power supply 60. The machines are equipped with local processing units 64, 68 and communication devices 69, 70 according to the present invention, and data regarding the machine properties. operating conditions and status, both instantaneous and historical, can be made available in a stationary processing unit 64 and / or a co-rotating processing unit 68 at each machine. A group of machine units 71 is generally controlled by a production line unit 66. According to the present invention, a number of communication devices 65 are established between the machine units 71, i.e. the stationary 64 and / or co-rotating processing units 68 of the machines, and the production line unit 66. For example, if a fault occurs in the network, or if the power demand is abnormal, the production line unit 66 may transmit information thereon to the various processing units 64, 68, possibly coupled with a request or request about being able to temporarily operate the machines in a special way. The respective processing units 64, 68 can in turn inform the production management unit 66 of their current operating condition and if any tendencies to network instability have been detected. powerful becomes such a production management unit 66 has access to the current Special configuration on the operating condition of the various machines, ie. for example to temperature measurements or other interesting quantities. The control of the synchronous machines 62 via the production line unit 66 can be based on internal measurement signals as well as local, regional and central input signals. Examples of internal measured quantities are temperature measured values from both stator and rotor.

The frequency is an example of an interesting locally measurable input signal to a production line unit 66, while examples of regional and global input signals can be various indicators, for example based on eigenvalue calculations, which indicate the risk of voltage instability. If the production management unit 66 has access to both the current operating condition of the various machines and stored information on how large design margins are to be used in each of the machines, this can be used to continuously update the operating plans for how to handle different types of faults. or operating situations. The update of operating plans can be based on mathematical relationships, for example in the form of optimization tools such as optimal load distribution, OPF, and stability indicators e.g. based on intrinsic value calculations as well as on measured, calculated or extrapolated data for the machine's response with respect to protection interventions and limiters. If the production management unit 66 knows that a certain machine has a large margin to utilize, this can be requested in the event of a fault situation, in order to perhaps be able to save other machines with a smaller margin in the network.

A database with data about the different machines is thus preferable.

The database includes i.a. the data measured with the sensors described above. Such information can at a later time be used for analysis to increase knowledge of the plant's behavior in both normal operation and in the event of disturbances. The data can also be used to analyze the plant's efficiency and to be able to plan future operating modes.

The database thus includes both historical information concerning the previous operation of the machines, but also information needed to achieve an appropriate control of the machines. The database can e.g. contain the machine's response to previous faults.

The information stored in the database can, as described above, be based on measured, calculated and extrapolated data as well as mathematical calculations, for example in the form of optimization tools and eigenvalue calculations. Measurement data and other information stored in the database can advantageously be time-marked, for example by using time indications via GPS satellites to synchronize the timing. Databases 10 15 20 25 .ï-sïo 516. 401. 27 'can be made available directly in the production management unit 66 and / or the local processing units 64, 68. The production management unit 66 therefore preferably comprises a memory means for storing the database.

The network communication device 65 can operate according to different communication methods according to the prior art. Such methods can be based on fixed connections in the form of Lex. metallic wires or ñberoptics, or on wireless transmission, such as radio or radio link. When interconnecting your production management units, one of the communication devices can be built up. Such a network contributes to alternative communication paths, which can be used in cases where one or more communication devices for some reason are not available.

Through appropriate combinations of redundant communication paths and storage of information in databases, the production management unit 66 can perform calculations and updates of operating plans, for example by extrapolating previous measurement data or results from eigenvalue calculations to estimate the condition of the machine, even if any communication devices and / or sensors the moment does not work.

The possibility of building a reliable network is of particular importance, for example in strained operating situations and during operational reconstruction after a major operational disruption.

As previously pointed out, the concept of utilizing construction margins can also be implemented at the electricity grid level. Bodies for control and monitoring of the electricity grid, a grid monitoring unit 72, are responsible for the operation of the electricity grid in general, and can in a corresponding manner as described above communicate with electric power plants, ie. production line units 66, or individual electrical machines 62, in order to obtain information on possible margins. These margins can then be used for an optimization of larger areas or the total operation of the electricity grid.

The information transmitted from an electric power plant or individual electric machine to a grid monitoring unit 72 at the power grid level should preferably be of a more summary type than lower down in the hierarchy. An electricity grid operator is above all interested in knowing the available power resources in various places in the grid and the possible costs associated with utilizing these. The detailed conditions regarding the machines' individual temperature margins are of less interest, especially for a hierarchically superior electricity network operator. It is also in the interest of an operator of an electric power plant to be able to limit the exchange of information, since some of the available information can be used as a means of competition against competing operators.

The main task of the nude monitoring unit 72 is to ensure the possibilities for a reliable and economically optimal operation of the electricity grid.

This may include communication of both information exchange and setpoints as well as control signals to both production control units 66, individual electrical machines 62 and power grids 60. Under normal operating conditions, the control of production control units 66 may be based on economic control signals, while direct control commands may be sent. purpose of saving the integrity and continuous operation of the electricity grid. The exchange of information between the network monitoring unit 72 and other units should take the form of messages, which in addition to the address and message may contain security keys (encryption) to restrict the right to access the information. By utilizing different authorization criteria for different units (users) in the communication system, adequate confidentiality against unauthorized dissemination of information can be obtained. The ability to decide which information each user has access to reduces the risk of unauthorized dissemination of sensitive information and enables, for example, partners to have access to more information than other completely external parties.

Thus, a preferred embodiment of a production line unit 66 in an electric power plant comprises at least one means for external communication. This means is arranged to partly receive and interpret messages from external units, such as e.g. an operator of an electricity network and send out selected information to the external units.

A possible communication sequence will now be described. An external unit sends a request if the electric power plant can increase its production of active power by 5%, and at what price this can be done.

The power plant's production management unit 66 responds with an offer at a certain price. If the external unit can accept the offer, an order is sent for increased power consumption. The power plant's production management unit 66 responds by implementing the promised increase and sending back a confirmation of the order.

Fig. 6 shows a circuit diagram for a basic control method for a synchronous machine according to the invention. The process starts in step 100. In step 102 a number of rotor quantities are measured, which are collected in a co-rotating processing unit in step 104. The co-rotating processing unit evaluates the measured values in step 106. Rotor information which is important for stationary parts, and external information which is important for the co-rotating processing unit is transferred between stationary and rotating parts in step 108. Based on the evaluated measurement results, the rotor current is then controlled in step 110 and the process is terminated in step 112.

Fig. 7 shows a circuit diagram of a basic control method for an electric power plant with at least one synchronous machine according to the invention.

The process starts in step 100. In step 102 a number of rotor quantities are measured in the synchronous machine, which are collected in a co-rotating processing unit in step 104. The co-rotating processing unit evaluates the measured values in step 106. Rotor information important for stationary parts of the synchronous machine and / or control, as well as external information that is important for the co-rotating processing unit is transferred between stationary and rotating parts in step 108. On the basis of the evaluated measurement results, the operation and power conversion of the electric power plant is then controlled in step 111 and the process is completed in step -1 12. 516 401 § 30 The person skilled in the art will recognize that various modifications and changes may be made to the present invention without departing from the scope of the invention as set forth in the appended claims.

Claims (32)

10 15 20 25 30 5.16 401 31 NEW PATENT CLAIMS A rotating electrical synchronous machine comprising a rotor (3) with windings (7; 38, 39); a stator (2); at least one sensor rotating with the rotor (3) (15-17,43-46); and at least one converter (8; 30; 40) for controlling the current in the rotor windings (7; 38, 39), and characterized by a processing unit (10; 68) rotating with the rotor (3), connected to the co-rotating sensor ( 15-17,43-46), for evaluating measurement data obtained from the co-rotating sensor (15-17,43-46) and for controlling the converter (8; 30; 40), which reduces the amount of data that must be transferred between the rotors (3) and the stator (2); a stationary processing unit (12; 64); and a communication means (1 1, 13; 69, 70), for wireless information transmission between the co-rotating processing unit (10; 68) and the stationary processing unit (12; 64). The rotary electric synchronous machine according to claim 1, characterized in that the information transmission of the communication means (11, 13; 69, 70) takes place with radio signals. The rotary electric synchronous machine according to claim 2, characterized in that the radio signals have a carrier frequency exceeding 100 MHz. The rotary electric synchronous machine according to claim 1, 2 or 3, characterized in that the wireless information transmission of the communication means (11, 13; 69, 70) is digital. 10 15 20 25 30 516. 401 62 The rotary electric synchronous machine according to any one of claims 1 to 4, characterized in that the co-rotating sensor (15-17.43-46) measures one of the quantities; rotor winding temperature, current in the rotor winding, in voltage in the rotor winding, partial discharges in the rotor insulation, rotor insulation resistance, rotor vibrations, shaft torque, and load angle. The rotary electric synchronous machine according to any one of claims 1 to 5, characterized in that the converter is a converter (8; 40) rotating with the rotor (3), connected to and controlled by the co-rotating processing unit (10; 68). The rotary electric synchronous machine according to any one of claims 1 to 5, characterized in that the converter is a stationary converter (30), connected to and controlled by the stationary processing unit (12; 64). The rotary electric synchronous machine according to any one of claims 1 to 7, characterized by at least one stationary sensor (18-20) connected to the stationary processing unit (12; 64), the stationary processing unit (12; 64) being arranged for evaluating network data obtained from the stationary sensor (18-20). The rotary electric synchronous machine according to claim 8, characterized in that the stationary sensor (18-20) measures one of the quantities: stator winding temperature, current in the stator winding, voltage in the stator winding, 51.6 401 when partial discharges in the isolation of the stator , stator insulation resistance, and phase angle. An electric power plant comprising a number of rotary AC machines (1, 62), a production line unit (66), and characterized in that at least one of the rotary AC motors (1, 62) is a synchronous machine according to any one of claims 1 to 9. The electric power plant according to claim 10, characterized by communication devices (14; 65) between the production line unit (66) and the stationary (12; 64) and / or co-rotating (10; 68) processing unit of the synchronous machine (1; 62). The electric power plant according to claim 10 or 11, characterized in that the communication device series (14; 65) comprises physical lines in the form of metallic lines or optical cables. The electric power plant according to claim 10 or 11, characterized! in that the communication devices (14; 65) comprise means for transmission via radio or radio link. The electric power plant according to any one of claims 10 to 13, characterized in that the production line unit (66) comprises means for transmitting messages to and from external units. A control method for rotary electrical synchronous machines, comprising the steps of: measuring quantities associated with the rotor (3); and controlling the rotor current of the synchronous machine (1; 62); and characterized by the steps: 10 15 20 25 30. 5 1 6 4 0 1 di: collecting the measured rotor quantities in a processing unit (10; 68) rotating with the rotor (3); evaluation, in the co-rotating processing unit (10; 68), of the measured rotor quantities; transmitting information wirelessly between the co-rotating processing unit (10; 68) and a stationary processing unit (12; 64); wherein the control of the rotor current of the synchronous machine (1; 62) takes place based on the evaluation of the measured rotor quantities, which minimizes the amount of data that must be transferred between the rotor (3) and the stator (2). The control method according to claim 15, characterized in that the control of the rotor current of the synchronous machine (1; 62) takes place through the co-rotating processing unit (10; 68). The control method according to claim 15, characterized in that the control of the rotor current of the synchronous machine (1; 62) takes place through the stationary processing unit (1 2; 64). The control method according to any one of claims 15 to 17, characterized by the further steps: measuring quantities associated with the stator (2); collecting the measured stator quantities in the stationary processing unit (12; 64); and evaluating, in the stationary processing unit (12; 64), the measured stator quantities. The control method according to claim 18, characterized in that the control of the rotor current of the synchronous machine (1; 62) takes place based on the evaluation of the measured stator quantities. The control method according to any one of claims 15 to 19, characterized in that the control of the rotor current of the synchronous machine (1; 62) takes place based on external instructions and / or on stored instructions and control parameters. 10 15 20 25 30, 516 401 55 ' The control method according to claim 20, characterized by the further step: modifying the control parameters for the control of the rotor current based on previous operating data. The control method according to any one of claims 15 to 21, characterized in that the transmission takes place with radio signals. The control method according to claim 22, characterized in that the radio signals have a carrier frequency exceeding 100 MHz. The control method according to any one of claims 15 to 23, characterized in that the transmission is digital. A control method for an electric power plant, comprising at least one synchronous machine (1; 62), comprising the steps of: measuring quantities associated with the rotor (3) of the synchronous machine; and controlling the power conversion of the power plant; and characterized by the steps of: collecting the measured rotor quantities in a processing unit rotating with the rotor (10; 68); evaluation, in the co-rotating processing unit (10; 68), of the measured rotor quantities, which minimizes the amount of data that must be transferred between the rotor (3) and the stator (2); transmitting information wirelessly between the co-rotating processing unit (10; 68) and a stationary processing unit (12; 64); whereby the control of the electric power plant's power conversion takes place based on the evaluation of the measured rotor quantities. The control method according to claim 25, characterized by the further steps: measuring quantities associated with the stator (2); 516,401 collecting the measured stator quantities in the stationary processing unit (12; 64); and evaluating, in the stationary processing unit (12; 64), the measured stator quantities. The control method according to claim 26, characterized in that the control of the power conversion of the electric power plant takes place based on the evaluation of the measured stator quantities. The control method according to claim 25, 26 or 27, characterized by the further step: grain granulation of data concerning the operation of the synchronous machine from the stationary (12; 64) and / or the co-rotating (10; 68) processing unit to a production line unit (66) associated with the electric power plant. ). The control method according to any one of claims 25 to 28, characterized by the further step: communicating instructions and / or requests regarding the operation of the synchronous machine (1; 62) from the production line unit (66) to the stationary (12; 64) and / or the co-rotating (10; 68) the processing unit. The control method according to any one of claims 25 to 29, characterized in that the communication between the production line unit (66) and the stationary (12; 64) and / or the co-rotating (10; 68) processing unit takes place via metallic wires or optical fibers. The control method according to any one of claims 25 to 29, characterized in that the communication between the production line unit (66) and the stationary (12; 64) and / or the co-rotating (10; 68) processing unit takes place via radio or radio link. The control method according to claim 30 or 31, characterized by the step: .516 401 ö? transmission of messages between the production management unit (66) and external units.